John's 991

I recently replaced the rotors and brake pads on my 991 CS. I used stock rotors and the Pagid RS 29 pads as I track the car regularly. If your curious, I wore out 3 sets of pads before I needed to replace the rotors, but they were very shot. In fact the rotors could have been replaced after the second set, but I was waiting for the Pagid pads to be available so I could do both at the same time.

As I did not want to swap out the Pagid pads for stock pads for driving on the street I used some Permatex 24125 Ceramic Extreme Brake lubricant in hopes of minimizing the squeal. The Permetex is a sticky purple grease that maintains the consistency of grease once applied (it does not dry like some products do). I put a thin, uniform coat to the back of the pads and let it sit for a couple of days to see if it would dry out, but it did not change consistency at all.

For those of you who are interested, it is very easy to change the pads and rotors on the 991. The wheels come off, the calipers come off with two bolts and the rotors come off with two small screws. Just don't forget to leave the e-brake off or strip the small screws. I used a pad spreader to push the pistons back in, and installed the new pads. I put masking tape on the brake pad material to ensure that no Permetex could get on the braking surfaces and used the pad spreader one more time to make sure everything was seated and the pistons were fully recessed then removed the tape.

I used a piece of wire to hold the calipers to the spring or strut while I was working, as its not a good idea let them hang by the brake hose. This is not necessary if you are just changing the brake pads, as its possible to hold them in one hand and install the pads with the other. But not possible when changing the rotors.

I wanted to see if removing the backing plates would help with cooling, so I took them off while the rotors were off. 3 small bolts for the fronts and 4 for the rears and off they come. I am not sure what good they serve, other then maybe keeping debris off the inside of the rotors, but if any of you know more I would love to hear. I can easily put them back the next time I replace the rotors.

Everything goes back the same way, and I replaced the caliper bolts and rotor screws, as recommended by Porsche (or at least according to Suncoast). The rotor screws seem like a good idea, the caliper bolts are probably overkill but i did them anyway. I then bled the brakes and have been using Castrol SRF brake fluid for awhile now as it has the highest boiling point I could find. Remember that there are two bleed screws on each caliper as the pistons on both sides squeeze the rotor.

Once it was all back together, I made sure to bed the brake pads by gently dragging the brakes gently while driving on the freeway to put a little temperature in them. On a deserted road, I then did 10 stops from 60mph to 10mph making sure to never come to a complete stop then 5 from 80mph to 10mph one immediately after the other. This gets everything hot and transfers a thin layer of pad material onto the rotors which helps them work better and reduce the squeal. I then drove for 20 minutes on the highway without touching the brakes to let them cool off and parked the car overnight.

So far I have driven the car on the street a handful of times and absolutely no squealing at all. I did repeat the bedding process a second time after driving on the street to ensure that there was a nice layer of material on the rotor, in case the street driving was wearing it off.

Initial impression of the pads is that they certainly have more bite to them than the stock pads, which is particularly noticeable which going slowly then stopping. I will be doing a track event in a few weeks and another in November, and am looking forward to seeing how the pads and removal of the backing plates will work compared to stock as well as how long the pads last. Hopefully they will not squeal after a hard couple of days on the track. More to come!

o2bcdn

Great information, thanks for posting!

I have a 2012 991S that has 7500 miles, including 6 track days (about 700 track miles). I just replaced my original pads with Porsche OEMs. After my most recent track day with the new pads (still on the original rotors) I have noticed a shudder every time I apply the brakes. I am thinking my rotors are warped - they still have thickness left, but the shudder is pretty strong at road speeds, so I'm worried about what it will be like at my track speeds. Did you experience any rotor issues or shuddering as your rotors wore out?

Please do share your ongoing experiences with the RS29s. I plan to make the switch to those when I replace my rotors and am anxious to hear about others' experiences!

John's 991

I suspect that the rotors are not warped, but you have uneven pad build up on them, which is causing the shudder. I had some of the same and it was improved after the next track day when I "burned it off." Bedding the pads should help with this in the future.

Unfortunately it never totally went away until I replaced the rotors. However, brake performance was not affected. I could brake as hard and late as ever. My 2012 has 6k miles, but a few more than 6 track days.

MayorAdamWest

I went with girodisc rotors, and they were much better. I had the same problems of shuddering and uneven wear as others on RL. Highly recommend the girodisc rotors and rs29 combo for the track.

John's 991

Adam West, thanks for your thoughts on the GiroDiscs. They look good, and will give them a try if I am not happy with the stock rotors. As they are 4x more than stock, I wanted to give this set up a try first.

Can you add more detail on how they are better? Also, did you remove the backing plates?

SB

Give it some time and they will start squealing. My RS29s started squealing only after after a track day followed by some street driving. BTW, I also used some copper grease on the backing plate to minimize the squealing...

NeoGeo07

To OP: Sometimes the backing plate acts as a heat shield and prevents rotors from spreading the heat to the control arms or the lower suspension linkage. Those are aluminum and could suffer damage if exposed to extreme heat. The road debris is the other reason. I don't think it helps too much with dissipating the heat from the rotors by taking them off. If you're experiencing fade you'll likely need brake ducts, not removing backing plates.

TrackDays247.com

BTW, we DO have the 991S pads IN STOCK - RS29s.

chuck911

Try cryo-treating your next set of rotors. They'll last longer and provide better and more consistent response. But really, anyone wearing them out this fast is overdriving the brakes. Pads and fluid are half-measures. You need brake ducts.

BradB

What is available for the 991?

John's 991

I wanted to report back after the first track day. The pads worked great, with a lot less fade than stock pads and a nice even feel. As suggested, they are squealing a bit more, but still not much. I can't tell if removing the backing plates has any part of this. I would love to have have brake ducts when as set are available.

If anybody knows of a set, would love to hear more. Also, how does one cryo-treat a set of rotors? I have used cryo-treated rotors on my last track car (E36 M3) and they did seem to make some difference.

shizzle

I've used the RS29 on OEM rotors for about 10 track days so far, and i'm extremely happy with them. I got them from Gruppe Werks - www.gruppewerks.com. They handle the heat really well, and I haven't had any fade even after 40 minute sessions. I haven't tried the Permatex grease, so my brakes do squeal quite badly.

John's 991

Shizzle, well after driving around, then a track day, and driving it some more, it is not squealing at all, although I hate to tempt fate. I got a few squeals at very slow speeds right before the track event, but I guess I built up enough pad material on the rotors or whatever the magic sent of circumstances might be to not have a problem.

I cannot say for certainty if it was the Permatex grease or breaking the pads in or both, but so far so good. Also, just as you report, they work great on the track. They hold up much better than the OEM pads even with the stock rotors.

Regarding the removal of the heat shields, the verdict seems to be out here. It would seem to me that it would help the heat dissipate a bit more, but interesting question about potentially damaging the surrounding suspension components. I will do some homework between now and the next time I swap the rotors. They are easy to take on or off.

And with any luck, maybe some after-market brake ducts will be available.

Jerry991

I put ceramic pads on my BMW to eliminate brake dust and there definitely is hardly any brake dust. The brakes aren't quite as responsive as the stock pads but a little more effort is worth eliminating brake dust and there was no squealing at all. I don't know if there are equivalent pads for 991s.

John's 991

Hi Jerry, I am only aware of two options for brake pads for the time being - OEM and Pagid. And my concern is not really with brake dust but track performance of the pads, ideally with minimal noise on the street.

Surely additional pads and probably rotors will be coming along in the following months.